This invention relates to a passive solar energy system. More specifically this invention relates to a thermal energy storage assembly which is visually transparent. Still more specifically, this invention relates to an assembly which can be used, as modules, to establish a visually transparent thermal energy storage wall for passive solar-heated buildings.
Interest in utilizing solar energy for space heating of buildings has increased substantially with the decreasing supply and increasing cost of fossil fuels for this purpose. Devices or systems for the utilization of solar energy are generally categorized as either active or passive. An active system utilizes solar collectors, some form of thermal storage and some means for circulating thermal energy between components. Although such systems are generally effective, they are expensive to install and require substantial maintenance.
The passive approach for solar heating of buildings has recently been recognized as an alternative to active systems because of relatively low cost, long-term reliability and operational simplicity. A passive system absorbs and thermalizes solar energy and then transfers heat through a thermal storage medium to the building heating load without the use of active components such as mechanical pumps. The more efficient passive systems tend to share the same space with the building interior as in the case of the Trombe wall system as described in U.S. Pat. No. 3,832,992 where a thermally massive concrete wall is located in the interior adjacent to the solar gain fenestration: generally facing toward the south. Sunlight is absorbed and thermalized on the wall's exterior-facing surface. Part of the resulting heat is stored in the wall and transferred to warm the interior by conduction, convection, and radiation.
Other passive systems utilize a water wall consisting of opaque or translucent containers of metal, fiberglass or plastic, filled with water and placed or stacked behind windows having a southern exposure as thermal energy storage units.
Both the concrete wall and the water wall storage systems block the entrance of light into the spaces to be heated and thus additional energy consumption may be required for lighting. Because of the necessary massive nature and weight of either a concrete wall or a stack of cylindrical storage containers filled with water, it is difficult, if not impossible, to retrofit existing houses or buildings with either of these passive solar storage systems.
Thus it is important that any passive thermal energy storage system have maximum flexibility to accommodate the general interior use requirements of buildings in the context of both retrofits and new construction. Therefore a suitable passive system should provide both high solar heating efficiency and flexibility for interior integration in a wide range of buildings types.